Kevin McCarthy, holding sign, and his husband David Bui, of San Francisco, join a crowd of thousands as they head down Castro Street during a march to protest the passage of Prop. 8 in San Francisco, Calif., on Friday Nov. 7, 2008.

Photo: Mike Kepka, The Chronicle

Kevin McCarthy, holding sign, and his husband David Bui, of San...

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Thousands of people head down Castro Street during a march and to protest the passage of Prop. 8 on Friday Nov. 7, 2008 in San Francisco, Calif.

Photo: Mike Kepka, The Chronicle

Thousands of people head down Castro Street during a march and to...

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Amanda Riley (L) and Sarah Garrett (R) both from Daly City march at a rally to protest the passage of Prop. 8 beginning at Market and 7th Sts. in San Francisco, CA., on Friday, November 7, 2008.

Photo: Liz Hafalia, The Chronicle

Amanda Riley (L) and Sarah Garrett (R) both from Daly City march at...

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Evan James from San Francisco at a rally to protest the passage of Prop. 8 beginning at Market and 7th Sts. in San Francisco, CA., on Friday, November 7, 2008.

Photo: Liz Hafalia, The Chronicle

Evan James from San Francisco at a rally to protest the passage of...

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Hundreds gather at a rally to protest the passage of Prop. 8 beginning at Market and 7th Sts. in San Francisco, CA., on Friday, November 7, 2008.

Photo: Liz Hafalia, The Chronicle

Hundreds gather at a rally to protest the passage of Prop. 8...

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Claire Henriksen and Maddie Kiutto, of San Francisco, Calif., share a kiss in Dolores Park after joining thousands of people in a march through the Castro district to protest the passage of Prop. 8 in San Francisco, Calif., on Friday, Nov. 7, 2008.

Photo: Mike Kepka, The Chronicle

Claire Henriksen and Maddie Kiutto, of San Francisco, Calif., share...

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Rose Johnson, of San Francisco, dances in Dolores Park after joining thousands of people in a march through the Castro to protest the passage of Prop. 8 in San Francisco, Calif., on Friday Nov. 7, 2008.

Photo: Mike Kepka, The Chronicle

Rose Johnson, of San Francisco, dances in Dolores Park after...

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Jeffrey Lowery and David Kramer, domestic partners from Fremont, Calif., hold candles in Dolores Park after joining thousand of people in a march through the Castro district to protest the passage of Prop. 8 in San Francisco, Calif., on Friday Nov. 7, 2008.

Photo: Mike Kepka, The Chronicle

Jeffrey Lowery and David Kramer, domestic partners from Fremont,...

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Raymond McKenzie and his 3 year old son, Bobby McKenzie, of San Francisco were two of several hundred protesting the passage of Prop. 8 beginning at Market and 7th Sts. in San Francisco, Calif., on Friday, November 7, 2008.

Photo: Liz Hafalia, The Chronicle

Raymond McKenzie and his 3 year old son, Bobby McKenzie, of San...

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Hundreds gather at a rally to protest the passage of Prop. 8 beginning at Market and 7th Sts. in San Francisco, CA., on Friday, November 7, 2008.

Thousands of demonstrators marched down Market Street in San Francisco on Friday night to protest the passage earlier this week of Proposition 8, which effectively bans same-sex marriage in California.

The march began around 5:30 p.m., as the group worked its way west toward its final destination of Dolores Park. A large group remained around Ninth and Market streets, holding signs, chanting and jamming traffic. About a dozen Muni buses were stuck in the traffic mess.

"Our rights have been taken away," said Debra Walker, a lesbian who has lived in San Francisco since 1981. She is a member of the city's building inspection commission and is the past president of the Harvey Milk Club.

"I came here because of the welcoming way of San Francisco. It is so troubling that in 2008, this would pass. The fear campaign was unconscionable."

Walker stood holding a banner across Market Street and said she was prepared to be arrested.

"A little traffic stoppage is mild compared to having rights taken away from you," she said.

There were no reports of arrests in connection with the demonstration.

The crowd shouted chants such as "Our rights" and "We will not be quiet."

One of the organizers of the demonstration, Ryan Kerian, 28, a gay lawyer and San Francisco resident, said the rally was designed to "show that we won't be silent.

"We've had rights stripped away from us," he said. "We aren't going to give up and go away."

The crowd was ethnically mixed, but two African American men infuriated many demonstrators by loudly arguing in favor of Prop. 8. They were berated repeatedly by opponents of the proposition, but spent more than 90 minutes arguing about the Bible.

"It is not discrimination," said Chauncey Killens, who said he represented a small congregation in Prunedale (Monterey County). He carried a sign reading, "Yes on Prop 8. Protect marriage."

The presence of the two men from Prunedale was deeply offensive to many of the demonstration participants, said Jeffrey Lebin, 52, of San Jose. "To have the lack of support from the black community is very painful to us. Fifty years from now, I think the black community will be ashamed that they didn't support us."

Uriah Findley, 27, who is straight and was born and raised in conservative Orange County, said he believes that Prop. 8 will be a fleeting event in California history.

"This is their last hurrah," he said. "Proposition 8 is the last gasp of a dying way of thinking."

He said religion has no place in laws.

"As far as I'm concerned, this isn't something that ever should have been voted on," he said.